Various rotation detecting apparatuses include a magnetic sensor for measuring magnetic change based on rotation of a motor, and generate information indicative of rotation of the motor based on the measured magnetic change.
For example, Japanese Patent Application Publication 2015-116964 discloses a typical one of these known apparatuses. Specifically, this JP Patent Publication discloses an electronic control unit for an electric power steering apparatus including a motor that generates torque for assisting a driver's turning effort of a steering wheel.
The electronic control unit includes first and second magnetic sensors, which are an example of first and second rotation sensors.
The first magnetic sensor measures magnetic change based on rotation of a motor, and outputs a first rotation signal indicative of the measured magnetic change. The second magnetic sensor, which is separately disposed from the first magnetic sensor, measures magnetic change based on rotation of the motor, and outputs a second rotation signal indicative of the measured magnetic change.
The electronic control unit also includes a control section that generates, based on the first rotation signal and the second rotation signal, information indicative of the rotational angle of the motor. Then, the control section calculates, based on the generated rotational angle information, the position of the steering wheel.